What do you mean by cladding ?

Explanation

**Step-by-Step Solution:**

1. **Definition of Cladding**: Cladding refers to the outer layer or coating that surrounds the core of an optical fiber.

2. **Structure of Optical Fiber**: An optical fiber consists of two main parts: the core and the cladding. The core is the central part through which light travels, while the cladding is the layer that surrounds the core.

3. **Material Composition**: The cladding is typically made of glass, similar to the core, but it has a slightly lower refractive index than the core. This difference in refractive index is crucial for the functioning of the optical fiber.

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